. This research is designed to evaluate and document the efficacy of a long-term intracranial pressure (ICP) monitoring system in clinical trials. Simultaneously, the interfacing between the sensor and the data acquisition system will be finalized. Additionally, the most effective between two alternative implantation techniques will be determined. Initial evaluation will be accomplished through laboratory testing in a simulated environment utilizing a hyperbaric chamber to demonstrate each sensor's ability to accurately track known pressure changes over its designed operating range. The system's ability to determine intracranial pressure by simultaneously measuring absolute cranial pressure and barometric presssure will then be tested through animal studies and experimental human implantation. The device allows telemetric transmission of information from the implanted sensor to the external data acquisition system, without the use of percutaneous connections. It is claimed that this will permit the use of the system for significantly longer periods of time than existing ICP monitoring systems and with less patient restraint. It is stated that the ability to monitor for longer periods of time is required for such conditions as hydrocephalus, pseudotumor, aneurysms, and approximately 20 percent of head trauma cases.